let arr1 = [1, 2, 3, { aa: 999 }]
let arr2 = Array.prototype.slice.call(arr1)
let arr3 = arr2
arr2[arr2.length - 1].aa = 888
arr3[0] = 9

console.log(Array(arr1.length - 1))
console.log(arr1)
console.log(arr2)
console.log(arr3)
